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The sound of strings

Here is part 2 of the series I am writing on the science behind music in “Saamagaana – The First Melody“, a monthly magazine on Indian Classical Music. The intent is to help readers understand a bit more about the science behind music and musical instruments and to enhance their appreciation of the same.

This is from the May 2015 issue of the magazine. Please contact the magazine for subscriptions.

The Sound of Strings

Just like human beings, instruments too belong to families. Instruments in a particular family are similar to each other. Often made of the same types of materials, they resemble one another, and also sound similar. R RAMKUMAR presents the second in the series on the physics of sound and how our brain perceives music, voices and musical instruments

Why do some singers stick a finger in their ear or cup their ear while singing?

Humans, in general, are not designed to hear their own voices too loudly lest this drowns out any other sound they should be paying attention to, like that of an approaching train. Closing a ear, say, by sticking a finger in the ear, helps improve the feedback between the mouth and the brain and also partially blocks external sounds.
Thus singers can hear their own voices better and also monitor their pitch better. This is especially helpful in large concert halls where there is noise/echo and also when the singer is performing in a group.

Why are most musical instruments made of strings or shaped like columns?

Remember? A musical sound or note is made up of ripple patterns that repeat and join together in an organized way.

This can be made to happen easily if the vibrating object has a simple shape. A column or a rod is one of the simplest shapes possible and can vibrate in just the right way to produce musical notes. This is why most musical instruments either have columns of steel (for example, strings in a violin) or columns of air inside tubes (for example, flutes).

I peeped into the green room before the concert and saw the violinist change some of the strings. Why did he do that?

Strings are thin, long columns of steel or some other suitable material. New strings usually produce loud, clear notes. As the violinist keeps playing on them, they gradually get worn out and become an imperfect column shape. The notes that get produced from such strings would sound weaker and may start becoming vague in pitch. This might have been the reason why you saw the violinist replace the strings. The strings might have also broken and required replacement.

If it is the string that produces the sound, then why does a violin or a guitar have a wooden body?

Vibrating strings hardly make any noise on their own as they are too thin and don’t push too much of air about. When strings are attached to a hollow box like the body of a violin or a guitar, their vibration are passed on to the wooden panels of the body which try to vibrate at the same rate as the string. This creates more powerful ripples in the air pressure, thus making louder sound.